The invention relates to a color wheel module for an image display device to modulate the color of light beams, and more particularly, to a color wheel module capable of preventing the spindle of the color wheel from being damaged during a balance process.
Image display devices are used to project image on a screen for viewing. A conventional image display device mainly includes an image generation device to generate various types of images. It needs a light beam that changes color at a high frequency to generate the color images. Conventional image display devices generally employ a color wheel to achieve this purpose.
The color wheel consists of a plurality of color filter sheets with different optical spectrum. Light beams passing through the filter sheets are filtered. Only certain spectrum of light is allowed to pass through and other spectrum of light will be reflected. By rotating the color wheel continuously, different color filter sheets are sequentially insert into the path of the light beam to provide sequential color change of the light beam at a high frequency. As the color wheel provides sequential color change of the light beam through rotation, the color filter sheet is usually designed in a fan shape for adhering to a carrier to form the color wheel. Then the color wheel is mounted onto a spindle of a motor.
There are many ways for mounting the color wheel known in the prior art, such as U.S. Pat. Nos. 5,868,482 and 6,024,453. Refer to FIG. 1 for a conventional color wheel. It has a carrier 11 coated with an adhesive layer 13 to bond to a color wheel 17 for mounting onto a spindle 22 of a motor 2. As the color wheel 17 requires high precision, balancing must be done after bonding to ensure that the color wheel 17 is not positioned eccentrically or does not wobble when rotating (to meet the quality requirements to conform to ISO G 6.3 of 1940 to 1973). However, in the conventional structures balancing is done only after the carrier 11 and the color wheel 17 have been mounted onto the spindle 22 of the motor 2. The most common approach for balancing is to have test rotation for the color wheel 17. A small amount of a substance is then filled into or removed from the unbalanced side. Either way, the color wheel 17 has already been mounted onto the spindle 22. The balancing process tends to apply some unwanted force on the motor 2 which may damage the spindle 22 of the motor 2. Take the example of removing the substance. A selected amount of substance has to be removed from the heavier side of the color wheel 17 to reach the desired balance. The most common way to remove the substance is drilling. Hence during the drilling process of removing the substance, the spindle 22 of motor 2 is subjected to stress and damage might occur. It could even result in reduced the life of the motor 2. Moreover, balancing is done after the color wheel 17 has been mounted onto the spindle 22. Because of the balancing process is done after the color wheel been junction together with the spindle 22 of the motor 2. Once the color wheel 17 is damaged and a new color wheel 17 is replaced, the balancing process has to be redone. In serious situations, if the balance process has caused damage or bias on the spindle 22, a great amount of effort must be devoted to make the new color wheel 17 reach the balance required. Sometimes balance can never be achieved, and the color wheel module 30 becomes useless.
The primary object of the present invention is to provide a color wheel module for an image display device to resolve the foregoing problems. The color wheel module is composed of a color wheel and a motor assembly. The color wheel is balanced before it is mounted with the spindle of the motor to prevent causing stress and damage to the spindle of the motor.
The color wheel module for an image display device according to the invention is adopted for use on an image display device to modulate the color of light beams. It consists of a spindle, a motor, a carrier, a color wheel and a connection ring. The spindle is mounted in the motor and driven by the motor for rotation. The carrier is coupled on the spindle and has a contact flange and a support section to form a trough therebetween. The connection ring is bonded to the color wheel. After the connection ring is bonded with the color wheel, balance may be performed. There is no restriction on the balance method. Substance may be removed by rotation methods. After balanced, the connection ring is installed in the base circle of the carrier. By controlling the precision diameter of the base circle, balance is no longer necessary when the color wheel is mounted onto the carrier. Thus the damage or bias of the spindle that might otherwise occur during the balance process is eliminated.